Both Facebook and Twitter have launched large counter-offensives to show that they’re taking action on the matter. In September, Facebook CEO Mark Zuckerberg announced the company was taking new steps to increase transparency and mitigate foreign influence on its platform.

Facebook has since addressed issues about transparency and election interference on its “Hard Questions” blog. The company’s chief operating officer, Sheryl Sandberg, also met with top lawmakers during a recent visit to Washington.

Twitter has not publicly involved its top executives in the Russia matter, though the firm’s co-founder and board member Ev Williams spoke to CNN about misinformation on its platform in September.

The company has said it is taking steps to keep foreign actors from manipulating its platform, including instituting new requirements that political ads be clearly labeled.

Twitter and Facebook have already briefed House and Senate Intelligence committee lawmakers and staffers on its findings regarding Russia’s election interference on its platform.

Google also briefed committee officials, but did so covertly.

While Google doesn’t have a widely used public facing social media platform like Facebook and Twitter, experts and lawmakers are still curious to know how it might have been used. A spokesperson for Warner’s office told The Hill in September that he was interested in whether foreign actors may have purchased ads on Google — which can be targeted to specific search terms — to influence Americans.

Digital media researchers also want to know what Google knows about how Russian actors might have used YouTube to disseminate information.

“Our understanding at the moment right now is that YouTube has been used for Russian propaganda from both sources like Russia Today, but also smaller sources and user-generated content,” said Lisa-Maria Neudert, a digital political communications researcher at Oxford University.

Nuedert said YouTube has taken down content from such smaller sources, making the extent of Russian influence hard to explore, but remnants of the footage still exist on the internet.

A 2015 New York Times Magazine profile of the Internet Research Agency — the Kremlin-linked group that Facebook revealed purchased 3,000 ads on its platform — details how it has used YouTube videos in the past.

In one instance, the Internet Research Agency used YouTube videos to help substantiate a hoax story about a nonexistent chemical plant explosion. The video is still on YouTube and has not been suspended or deleted.

It’s unclear whether Google and YouTube will release more information about Russia, but lawmakers believe that the hearings will shed new light on how foreign actors have taken advantage of it and its competitors’ platforms.

“I think people will be surprised when they see the breadth of how many Americans got touched by these communications,” Warner told The Hill last Wednesday. “I don’t think the press reports have reported the extent.”